Human colonic epithelial cells have proven rather resistant to growth in tissue culture compared, for example, to other epithelial cells from skin and breast. For that reason most studies on colonic epithelial cells have been performed using organ culture of tiny, millimeter sections of the epithelial layer (Autrup, H., et al. (1978) Gastroenterology 74:1248-1257; Browning, T. H., et al. (1969) J. Clin. Invest. 48:1423-1432; Deschner, E., et al (1963) J. Clin. Invest. 42:1922-1928; Deschner, E., et al. (1972) J. Natl. Cancer Inst. 48:1567-1574; Eastwood, G. L., et al. (1973) Gastroenterology 64:375-382; Usugane, M., et al. (1982) Digestion 24:225-234). Very recently a new method of culturing colonic crypts and crypt fragments in suspension culture has been described (Moyer, M. P., et al. (1983) Proc. of the Soc. for Exp. Bio. and Medicine 174,12-15). In both cases there is difficulty in visualizing single cells for analysis, as these methods maintain the three-dimensional crypt structure, a hollow cylinder of roughly 600 to 800 epithelial cells.
The organ culture biopsies are embedded and then sectioned from the base to the top of the crypt, a laborious procedure for processing numerous biopsies. However, such studies have shown that patients at very high risk for developing colon cancer because of inherited genes, and genetically low-risk individuals in cancer-free families, exhibit differences in the distribution within the colonic crypt of their DNA synthesizing cells. Differences in the location and the fraction of replicating cells have proven to be the earliest preneoplastic alterations seen during the evaluation of human colon cancer (Deschner, E., et al. (1975) Cancer 35:413-418; Lipkin, M., et al. (1974) Cancer 34:878-888; Lipkin, M., et al. (1983) Cancer Research, 43:1899-1904).